http://www.fiftyplusforum.co.uk/devtest3/index.php?action=verificationcode;rand=1fadeb85c22ab374728a6532c5fb3d3fYou can see there is one hell of a difference. It would appear that something is corrupting the code for the image. The images are there and are accessible.

You say this only occurred when you changed hosts. Did you change the cookie name?